Existing ball valve generally includes a main valve body, an auxiliary valve body, a valve stem, a ball, a spring, and a valve seat. The valve stem is mechanically combined with the ball. The ball and the valve seat are used as sealing elements. The ball is spherically fitted with the valve seat. The ball is capable of being rotated at 90 degrees in the valve body with the valve stem serving as a rotating shaft, so as to open the channel (pipeline) of the valve body or close it to prevent media from flowing in the channel. The force of the spring keeps the ball in close contact with the valve seat.
The disadvantage of the foregoing ball valve is that, since the main valve body is connected with the auxiliary valve body through flanges, the assembly or disassembly of internal parts can be achieved only after the flanges of the main valve body and the auxiliary valve body were released, which makes the valves on pipeline, especially welded valves under high temperature and high pressure, difficult to be operated.